1. Field of the Invention
The present invention relates to a power amplifier capable of significantly reducing a delay phenomenon caused by applying an input signal in the case that sufficient bias voltage is not supplied to an amplification device.
2. Description of the Related Art
A power amplifier, a circuit amplifying a predetermined input signal to generate an output signal, has been widely used to amplify power in electronic devices or wireless communication device communication signals. The power amplifier may include an amplifier circuit amplifying an input signal to be amplified to generate an output signal and a bias circuit applying a bias signal for operating the amplifier circuit in a voltage or current mode.
Generally, power amplifiers are configured of a plurality of devices such as an operational amplifier, a transistor, a resistor, or the like. In particular, since a device such as the transistor has characteristics the same as those of a switching device, a delay may occur due to a switching operation in each device when a signal is transferred through a plurality of transistors. In particular, when an output from a circuit unit applying an input signal to the amplifier circuit and an output from a bias circuit unit generating a bias signal for operating the amplifier circuit are not synchronized with each other, or the bias signal that is an output from the bias circuit unit is not sufficiently rapidly generated from the time at which the input signal is generated, even in the case that the input signal is applied to the amplifier circuit, the input signal may not be amplified, since the bias signal for operating the amplifier circuit may not be applied.
For example, in the power amplifier configured by a plurality of switching devices, the bias signal output from the bias circuit is applied to a gate or a base of the transistor. However, in a case in which the bias signal applied to the gate or the base of the transistor in the bias circuit is not synchronized with the input signal, or in a pedestal period in which the bias signal is applied later than the input signal, or the like, a delay phenomenon of signal amplification occurs within the power amplifier, which may have an adverse effect on power calibration in the entire system.